At the beginning of the episode, we see Rana advertising a Pokémon dress-up contest where Pokémon can dress up as other Pokémon and see how well they can imitate other Pokémon. The winner receives an exquisite Pokémon egg. Of course no one knows what could hatch from the egg. The camera men move up towards Rana. Rana then prepares for some special coverage on her show, "Sinnoh Now!"

The Sinnoh Now! show starts. Rana walks onto stage and greets the audience. She introduces herself and the contest. When the introduction is over, she lets the judges walk onto stage. The three judges are Officer Jenny, Nurse Joy, and Mr. Sukizo. Ash and co. are in the audience. Dawn states that the contest is so popular that it gets a very high ranking. The narrator states that Ash and co. have decided to stop at the contest along the way to Eterna City. Rana then signals the crew to change the TV screen to point to the registration desk. Two people (Jessie and James in disguise) are planning to win the contest. Jessie talks in her cowboy accent and states that she plans on winning the contest. Rana tells them that only Pokémon are allowed to enter the contest. Jessie is disappointed by this, but then she decides to enter Meowth in the contest.

Rana decides to take a break and a commericial begins. The TV displays an ad about the new Pokétch. Ash runs out of the room, and Dawn and Brock follow him. Ash tells his friends that he wants to register for the dress-up contest. Ash thinks it will be very fun, and the Pokémon egg seems like a great prize to him. Now Dawn and Brock also want to register after having the feeling of winning a Pokémon egg. Before they can run any further, Dawn stops Ash and Brock. Dawn tells them that they have to first decide which Pokémon they should enter. Rules state that a coordinator can only use one Pokémon. So Ash, Dawn, and Brock send out all of their Pokémon to make the decision. Ash tries to visual his Pokémon as other Pokémon, but he knows that they won't win. Suddenly, Pikachu tells Ash that it wants to enter. Pikachu then begins making facial expressions of Wobbuffet, Loudred, Buneary, Lotad, and a few others. So Ash decides to go with Pikachu, Dawn with Piplup, and Brock with Croagunk.

The contest begins. Many Pokémon such as Suicune, Swalot, Sunkern, and others show off their expressions to the judges. The judges hold up signs to indicate whether they liked the performance or not. Brock soon comes on stage. He has Croagunk dressed up as a Politoed. Croagunk flaps its arms just like a Politoed would. The three judges all liked Brock's performance. Up next is Jessie and Meowth, who is dressed up as a Weavile. The audience loves Meowth's imitation of Weavile. The judges also love it. Jessie states that her Meowth can imitate the voice of any Pokémon. She shouts out a few names, and Meowth imitates them well. Up next is James and his Mime Jr. James has Mime Jr imitate a Claydol and a Pokémon using Razor Leaf. James and Mime Jr also receive a perfect score from the judges.

The winner from the last contest enters the stage. The trainer has a Chatot who can sing Jigglypuff's song. After the singing Chatot is Dawn and Piplup, who is dressed like a Weedle. The audience also likes Piplup. Piplup is excited, and it accidentally uses Bubblebeam. Because Weedle can't actually use that attack, Dawn loses. Up next is Ash and Pikachu. Pikachu begins to take the shape of many different Pokémon. The audience and judges all love it. Ash is the last coordinator. Rana explains that the winner will be announced right after a short commericial break.

In the lobby, all the coordinators are discussing their strategies with their Pokémon. Jessie notices that James and Mime Jr are having an excellent time. She wants Meowth to do a bit better in the next round because she knows the competition will be tough. Jessie dresses Meowth up in the Sunflora disguise. With that, Jessie plans on winning the Pokémon egg. Meowth states that they can then give the egg to the boss for some extra money. Jessie cuts Meowth's dream. She states that they have to first find out what Pokémon lies inside the egg. Jessie hopes that it's a legendary Pokémon.

The final round is about to begin. Ash, Brock, Jessie, and James all made it in the finals. Piplup is sad that it didn't make it to the finals, but Dawn promises it that they will make it in next year. The first trainer up is the trainer with the singing Chatot. The trainer holds up a picture of a Lapras and tells it to sing something different. The Chatot sings the same Jigglypuff song but in a Lapras tone. Meowth tells Jessie that they don't really need to win the contest. They can just steal the egg when no one is looking. Jessie likes Meowth's idea. Jessie and Meowth creep up close to the egg case. While no one is looking, Meowth steals the egg from the case. Then Jessie begins to pull James away. Rana wonders where they are going. Croagunk notices that the egg is missing. Ash and Brock accuse Jessie and James of stealing the egg. Team Rocket begins to run away. Officer Jenny sends out Growlithe. Growlithe blocks Team Rocket's path.

Team Rocket begins to recite their motto. Ash demands that Team Rocket gives back the egg. Jessie refuses to give up the egg. She sends out Seviper, and Seviper uses Haze. Ash sends out Staravia. Staravia uses Gust to blow the haze away. When the haze has fully disappeared, Team Rocket has already made their escape. Ash and co. decide to track down Team Rocket. Dawn and Piplup follow them too.

Team Rocket has taken off in their balloon. Ash and co. run outside, and they demand for the egg back again. Team Rocket refuses to give the egg back. The TV crew are in a helicopter filming the event with Team Rocket. Ash orders Pikachu to use Thunderbolt, but Brock stops him. Brock states that the attack might damage the egg. So Staravia charges towards Team Rocket with a Wing Attack. Jessie sends out Dustox. It uses Poison Sting on Staravia, but Staravia dodges the attacks. Dawn orders Piplup to use Bubblebeam on Dustox. James tells Mime Jr to use Mimic. Both Pokémon use Bubblebeam and the attacks collide into each other. Rana notices that Mime Jr has a powerful Mimic attack. James is happy with the compliment, but Jessie says that she has seen better. This gets James mad. He orders Mime Jr to use Teeter Dance. Soon Meowth and Dustox become confuse.

With no one steering the balloon, the balloon begins to fall towards the ground. Ash and co. know that the egg will break if Team Rocket crashes to the ground. Meowth accidentally knocks the egg out of the balloon. Ash gasps as the egg begins to fall. Using some quick thinking, Dawn sends out Buneary. Buneary uses its Bounce attack to grab hold of the egg and bring it down safely. With the egg out of Team Rocket's possession, Pikachu finally uses Thunderbolt on them. Team Rocket blasts off again.

The contest comes to a close, and the winner is about to be decided. The trainers remaining are Ash, Brock, and the trainer with the Chatot. Officer Jenny announces that the winner is Brock and his Croagunk. Mr. Sukizo presents Brock with the Pokémon egg. Ash congratulates Brock for his win. Rana then makes her closing statement, and the contest finally comes to an end.

English Official Summary

What could convince our heroes to take a time-out from their journey to Eterna City? A Pokémon Dress-Up Contest where Pokémon try to imitate other Pokémon! Ash and Pikachu, Dawn and Piplup, Brock and Croagunk, even Team Rocket—they're all entering the contest in hopes of winning the Pokémon Egg prize! But will any of them be able to beat the reigning champion, a singing Chatot? In this contest, the key is to stay in character. So when Piplup, pretending to be Weedle, gets a little too excited and uses Bubblebeam, Dawn and Piplup are knocked out of the first round. Ash and Brock make it into the second round along with Team Rocket, and James wants to win the contest fair and square. But to his dismay, dishonorable duty calls: Jessie can't resist stealing the prize Pokémon Egg, forcing Team Rocket to make a quick getaway. Together with Officer Jenny, our heroes chase after Team Rocket so quickly that Brock's Croagunk doesn’t even stop to take off its Politoed costume! There's no doubt who’ll win this showdown, especially once Mime Jr.'s Teeter Dance hits Team Rocket instead of its target. In all the confusion, Team Rocket drops the stolen Pokémon Egg. Buneary quickly catches it, Team Rocket is sent packing, and everyone returns to the contest for the final results. After the judges tally their votes, the final winner is Brock's Croagunk, who stayed in character as Politoed even while chasing Team Rocket! Brock accepts his Pokémon Egg, leaving him and his friends to ponder two important questions. When will the Egg hatch—and just what Pokémon will it turn out to be?

French Official Summary

Qu'est-ce qui pourrait motiver nos héros à faire un détour pendant leur voyage vers Vestigion ? Un Concours d'imitation Pokémon où les Pokémon essayent de singer leurs semblables, bien sûr !

German Official Summary

Unsere Helden erfahren vom Deko-Spaß-Wettbewerb, einer ungewöhnlichen Veranstaltung, auf der sich Pokémon als andere Arten von Pokémon verkleiden!

Italian Official Summary

Cosa potrebbe convincere i nostri eroi a prendersi una pausa dal loro viaggio verso Evopoli? Ma naturalmente una gara di travestimento in cui i Pokémon cercano di imitare altri Pokémon!

Portuguese Official Summary

Nossos heróis descobrem um Torneio de Imitações Pokémon, um evento único onde Pokémon competem se disfarçando como outros tipos de Pokémon!

Finnish Official Summary

Sankarimme törmäävät Pokémonien pukeutumiskilpailuun, jossa Pokémonit kilpailevat pukeutumalla toisiksi Pokémoneiksi!

Spanish Latin America Official Summary

Nuestros héroes descubren un Concurso de Disfraces Pokémon, un evento único donde los Pokémon compiten disfrazándose de otros tipos de Pokémon.

Spanish Official Summary

¿Qué podría convencer a nuestros héroes para que se tomasen un descanso en su viaje a Ciudad Vetusta? ¡Un Concurso de Disfraces Pokémon donde los Pokémon tratan de imitar a otros Pokémon!

English Great Britian Official Summary

What could convince our heroes to take a time-out from their journey to Eterna City? A Pokémon Dress-Up Contest where Pokémon try to imitate other Pokémon! Ash and Pikachu, Dawn and Piplup, Brock and Croagunk, even Team Rocket—they're all entering the contest in hopes of winning the Pokémon Egg prize! But will any of them be able to beat the reigning champion, a singing Chatot? In this contest, the key is to stay in character. So when Piplup, pretending to be Weedle, gets a little too excited and uses Bubblebeam, Dawn and Piplup are knocked out of the first round. Ash and Brock make it into the second round along with Team Rocket, and James wants to win the contest fair and square. But to his dismay, dishonorable duty calls: Jessie can't resist stealing the prize Pokémon Egg, forcing Team Rocket to make a quick getaway. Together with Officer Jenny, our heroes chase after Team Rocket so quickly that Brock's Croagunk doesn’t even stop to take off its Politoed costume! There's no doubt who’ll win this showdown, especially once Mime Jr.'s Teeter Dance hits Team Rocket instead of its target. In all the confusion, Team Rocket drops the stolen Pokémon Egg. Buneary quickly catches it, Team Rocket is sent packing, and everyone returns to the contest for the final results. After the judges tally their votes, the final winner is Brock's Croagunk, who stayed in character as Politoed even while chasing Team Rocket! Brock accepts his Pokémon Egg, leaving him and his friends to ponder two important questions. When will the Egg hatch—and just what Pokémon will it turn out to be?

Russian Official Summary

Наши герои участвуют в конкурсе на переодевание покемонов. В нем покемоны должны переодеться так, чтобы стать похожими на других покемонов!

Dutch Official Summary

Onze helden ontdekken de Pokémon Verkleed-Wedstrijd, een uniek evenement waarbij Pokémon strijden door zichzelf te vermommen als andere Pokémon!

Norwegian Official Summary

Våre helter oppdager Pokémon-utkledningskonkurransen, et unikt arrangement der Pokémon konkurrerer ved å forkle seg selg som andre slags Pokémon!

Swedish Official Summary

Våra hjältar upptäcker en Pokémon-utklädningstävling, en unik tillställning där varje Pokémon tävlar genom att klä ut sig till andra sorters Pokémon!

Danish Official Summary

Vore venner opdager Pokémon-udklædningskonkurrencen, som er en enestående begivenhed, hvor Pokémon konkurrerer om at klæde sig om som andre slags Pokémon!